It's recommended to run your emacs as a server as "emacs --daemon" although the edit-server will happily run in a long-running emacs just as well.

your will find a button at the bottom of textarea when you browse the webpage

when you press the button a emacs frame will show up, with text already in the textarea

when you have done, press c-c c-c as "edit-server-done" to update your change to the textarea

Warning When you edit textarea, it is likely your change your major mode to mediawiki-mode or other major mode, this will likely bound the c-c c-c to other commmand, then you should use m-x "edit-server-done" - this should be fixed in the latest v1.11

Chrome extension Edit with Emacs uses its own Edit Server rather than Emacsclient because Chrome's security policy does not allow extensions to spawn new processes. The extension allows the user to edit text in Emacs and send the results to the browser textarea with [C-x #] (or M-x edit-server-done).